1. Technical Field
The present invention generally relates to an electric motor and a recording disk driving device including a motor, and more particularly relates to a stator for a motor.
2. Description of the Related Art
Conventionally, a recording disk driving device such as a hard disk drive includes a spindle motor (hereinafter referred to as a motor) which rotates a recording disk. These days, recording disk driving devices are installed in portable music players and many other portable devices, and there is a great demand for the recording disk driving device which has more storage capacity, and reduced thickness and dimensions. Whereby, in order to make the motor thinner and smaller, it is desired to make the motor thin and small.
It is known in the art that a portion of the stator of an inner rotor motor are arranged below a moving range of a magnetic head, reading/writing information from/to a recording disk, in order to reduce the size of the recording disk driving device.
Concerning about the motor in which the moving range of the magnetic head ranges over the portion of the stator, typically, winding height of wires wound around each tooth of the stator is substantially equal. Because of the configuration, a portion of an upper space of the stator (such as space between a coil and the recording disk, and space between a magnetic shield and the recording disk) other than the moving range of the magnetic head is vacant. However, it is difficult to reduce the thickness of the motor in amount of the vacant space while securing the moving range of the magnetic head.
The thickness of the motor may be reduced by reducing winding number of the coil around the teeth of the stator. However, upon reducing the winding number, torque of the motor is reduced as well. The winding number can be maintained by making an outer diameter of the stator bigger, but it results in making the motor bigger.